1 Nuclear Chemistry
Radioactivity 2 One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie (1876-1934). She discovered radioactivity or radioactive decay, the spontaneous disintegration of the nuclei of some elements.
Radioactivity or 3 Radioactive Decay The property in which an unstable nucleus gives off particles and/or energy This changes the atomic number (p + ) and forms a new element
Radiation 4 The penetrating rays (energy or particles) emitted by a radioactive source
Radioisotopes 5 Unstable isotopes that undergo radioactive decay Elements with atomic number 83 and up are radioactive Bismuth and beyond..
Nuclear Reactions vs. Normal Chemical Changes 6 Normal Chemical Reactions involve rearranging atoms. The elements don t change. Nuclear reactions involve the nucleus The nucleus opens, and protons and neutrons are rearranged The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together called binding energy
Mass Defect 7 Some of the mass can be converted into energy Shown by a very famous equation! E=mc 2 Energy Mass Speed of light
8 Types of Radiation Alpha (α) a positively charged helium nucleus Beta (β) an electron Gamma (γ) pure energy; called a ray rather than a particle 4 2 0 1 0 0 He e γ
9 Other Nuclear Particles Neutron Positron a positive electron Proton usually referred to as hydrogen-1 1 n 0 0 +1e 1 H 1 Any other elemental isotope
Penetrating Ability 10
Balancing Nuclear Reactions In the reactants (starting materials on the left side of an equation) and products (final products on the right side of an equation) 11 Atomic numbers must balance and Mass numbers must balance Use a particle or isotope to fill in the missing protons and neutrons
Alpha emission Nuclear Reactions 12 Note that mass number (A) goes down by 4 and atomic number (Z) goes down by 2. Nucleons (nuclear particles protons and neutrons) are rearranged but conserved
Nuclear Reactions 13 Alpha emission Try this one: Po 210 undergoes alpha radiation
Beta emission Nuclear Reactions 14 Note that mass number is unchanged and atomic number goes up by 1.
Nuclear Reactions 15 Beta emission Try this one: Uranium 238 undergoes beta decay
Nuclear Fission 16
Nuclear Fusion 17
Nuclear Reaction 18
Nuclear Power Plants 19
20 SO YOU SAY YOU WANT TO MELTDOWN YOUR OWN POWER PLANT? HERE S YOUR CHANCE TO PLAY HOMER SIMPSON.
21 Nuclear Power Pros and Cons Lot s of energy No green house gases Uses very little fuel Very small chance of massive disaster Potential target for terrorists Nuclear waste
22 Accidents can happen The worst nuclear accident in US history occurred on Three Mile Island in PA 1979 The reactor meltdown was caused by several mechanical errors as well as human error creating a coolant leak The reactor that had the melt down is no longer in use. The other reactor is slated to remain in use until 2034 London Calling by The Clash is about this accident
Chernobyl April 1986 23 Chernobyl Nuclear Power Plant Pripyat, Ukraine; April 1986 During a test, the reactor received a power spike, causing several explosions Radiation was picked up several hundred miles away, prompting the Soviet Union to admit the accident, 3
Japan Fukushima Power 24 Plant March 2011
25 Radiation Detection Film Badges exposure of film measures radiation exposure Geiger Counters- detect radiation through electric pulses in ionized gas Scintillation Counters- measure radiation from substances that emit visible light when energy is absorbed
Radiation Detection 26
27 Uses of Radiation Radioactive dating can determine the approximate age of an object There are many uses of radiation in the medical field Detect and kill cancerous cells X-Rays Many others Disinfect foods
Personal Dose Chart 28
Effects of Radiation on the Body 29
Half Life 30 Time it takes for ½ a sample to decay No two radioisotopes decay at the same rate Can be as short as a few seconds or take billions of years.
31
32
Half Life 33 Uranium-238 has a half-life of 4.5 billion years. It s stable ending element is lead (Pb)
Half Life 34
Half Life 35
Half Life 36 A 2.5 g sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The halflife of Sr-90 is 28 years. a) How many years will it take for 0.625 grams of Sr-90 to remain? b) What year will this be?
Half Life 37 A 2.5 g sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The halflife of Sr-90 is 28 years. a) How many years will it take for 0.625 grams of Sr-90 to remain? 56 years b) What year will this be? 2016
Half Life 38 The half-life of an isotope is 3.0 years. If 20 mg of this isotope disintigrates over a period of 12 years, how many mg of this isotope will remain?
Half Life 39 The half-life of an isotope is 3.0 years. If 20 mg of this isotope disintigrates over a period of 12 years, how many mg of this isotope will remain? 2.5 mg